Direct approach to realising quantum filters for high-precision measurements

Bentley, Joe; Nurdin, Hendra; Chen, Yanbei; Miao, Haixing

doi:10.48550/arxiv.2002.07644

Cited by 1 publication

(1 citation statement)

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“…5, in magenta and purple curves; aside from quantum noise, we have only included ĉ-oscillator thermal noise. This significant potential for improvement motivates further studies into this direction [45,46]. Application to microwave axion detectors.-For an axion detector consisting of a stationary magnetic field B 0 and a single mode of a microwave resonator, the interaction Hamiltonian can be written as Vaxion = α axion (Ψ 1 â1 + Ψ 2 â2 ) where â1,2 are the mode quadratures, and Ψ 1,2 are two quadratures of the oscillations of the axion field A(t) = Ψ(t)e −iω 0 t + Ψ * (t)e iω 0 t with…”

Section: φ(T)mentioning

confidence: 99%

Broadband sensitivity improvement via coherent quantum feedback with PT symmetry

Goryachev

et al. 2020

Preprint

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A conventional resonant detector is often subject to a trade-off between bandwidth and peak sensitivity that can be traced back to quantum Cramer-Rao Bound. Anomalous dispersion has been shown to improve it by signal amplification and is thus more robust against decoherence, while it leads to instabilities. We propose a stable quantum amplifier applicable to linear systems operating at the fundamental detection limits, enabled by two-mode non-degenerate parametric amplification. At threshold, one mode of the amplifier forms a PTsymmetric system of original detector mode. Sensitivity improvements are shown for laser-interferometric gravitational-wave detectors and microwave cavity axion detectors. Introduction.-Oscillators are often used to measure weak classical forces. In the early days of gravitational-wave (GW) detection, excitations of mechanical oscillators (resonant bars) were read out by inductive, capacitive [1] or parametric [2] transducers and via a superconducting quantum interference device (SQUID) amplifer [1-3]. A more sensitive technique is to read out the phase fluctuations in a light beam (Michelson and Fabry-Perot type interferometers) [4-6] using photodetection. Signal recycling [7] and Resonant Sideband Extraction (RSE) [8] techniques were designed optimize GW sensitivity by tailoring the optical frequency response. In this process, Mizuno noticed a trade off between bandwidth and peak sensitivity [9] -analogous to the gain-bandwidth product in electronic amplifiers [10]. Braginsky et al. [11,12] showed 1 , using the energy-phase uncertainty relation, that the power spectral density of equivalent spacetime strain noise is S h (Ω) ≥ 4 2 /S E (Ω) where S E is the spectral density of energy in the cavity, andThis integral embodies a bandwidth-sensitivity trade-off. This was also obtained by Tsang, et al. using Quantum Fisher Information [13], and further elaborated in Refs. [14][15][16][17]. For coherent states, ∆E 2 = ω 0 E, and in this case Eq. ( 1) is also referred to as the Energetic Quantum Limit (EQL) for GW detection 2 . The EQL trade-off applies to all quantum metrology experiments that use oscillators at coherent states.Detectors.-In this paper, we consider two types of detectors. GW detectors (of the laser interferometer type [6]) use optical resonators to increase the interaction between the spacetime

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Section: φ(T)mentioning

confidence: 99%